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Polar bears are in danger of extinction as well as many other species. There are 19 recognised subpopulations, and estimates place their numbers at about 20, to 25, Yet some claim that polar bear numbers have increased since the s and are now stable.
So what is the situation for this species? First of all, a few points need to be made about polar bear numbers: Nobody really knows how many bears there were in the s and s.
Estimates then were based on anecdotal evidence provided by hunters or explorers and not by scientific surveys. Polar bears are affected by several factors, including hunting, pollution and oil extraction.
Most notably, hunting, particularly following the introduction of snowmobiles, airplanes and ice breakers, led to a huge decline in certain subpopulations. The introduction of the International Agreement on the Conservation of Polar Bears inwhich restricted or even banned hunting in some circumstances, consequently resulted in an increase in polar bear numbers.
Not all subpopulations are affected to the same degree by climate change, and while some subpopulations are well studied, for others there is insufficient data to make broad statements about current and past numbers. With this caveat in mind, what do the figures actually say?
Figure 1 below compares the data for and Subpopulation status of polar bears for and Source: Polar Bear Specialist Group Both habitat degradation and over-harvesting are responsible for the decline in some subpopulations. To understand why the IUCN and US Endangered Species Act consider polar bears to be at risk, it is important to look at how rising temperatures are likely to affect their habitat in the future.
Polar bears are highly specialised mammals which rely heavily on sea ice for food and other aspects of their life cycle.
Satellite data show that Arctic sea ice has been decreasing for the past 30 years, and projections show that this trend will continue as temperatures carry on rising. The changes in sea ice affect polar bears in several ways: The early retreat of summer sea ice means that bears have less time to hunt and therefore less time to build up fat reserves.
The fragmentation and reduction in sea ice has several impacts. It forces the bears to swim longer distances, using up some of their fat reserves. And it also forces the bears to spend more time on land, with increased interactions with humans potentially leading to higher mortality.
A good example is the western Hudson Bay subpopulation, which is one of the best studied. Here, ice floe break-up is taking place earlier than 30 years ago, effectively reducing the feeding period by about three weeks.Many attacks by brown bears are the result of surprising the animal, which is not the case with the polar bear.
Polar bears are stealth hunters, Third, the recent effects of climate change have affected sea ice abundance in different areas to varying degrees.
Polar bears (Ursus maritimus) are the poster child for the impacts of climate change on species, and justifiably so.
To date, global warming has been most pronounced in the Arctic, and this trend is . Prof Charlotte Lindqvist, an expert in polar bears and climate change at the University of Buffalo, tells Carbon Brief: “[The data] shows a significant decline in sea ice throughout the entire polar bear range over the last 35 years, and if this trend continues the future looks dire for the polar bear species.”.
The study showed that the worst polar bear population decrease happened between and During that time, only 2 out of 80 cubs survived.
Usually, bear cubs have about 50% survival rate. Polar Bear Fertility Jenssen, the senior author of the other study released this month in Environmental Research, and other researchers extracted blood samples from polar bears tranquilized from darts filed from helicopters in the remote Norwegian archipelago of Svalbard, which sits about halfway between that country and Greenland.
How Polar Bears are affected by Global Warming? P olar bears are one of the few Arctic animals that rely on sea ice for their prey. As the Arctic sea .